The present invention is based on a control device for controlling a hydraulic cylinder unit, wherein the control device has a controller which receives, on its input side, a setpoint variable and an actual variable and determines, on the basis of the difference between the setpoint variable and the actual variable, a preliminary manipulated variable for a valve control unit of the hydraulic cylinder unit.
Hydraulic cylinder units exhibit a control behavior which is strongly dependent on the operating point of the hydraulic cylinder unit. A controller that has been optimized for a specific operating point operates less well or badly at other operating points.
To improve the control behavior it is known in the related art that what is referred to as a butterfly curve is used as a control characteristic of the controller. The butterfly curve however does not cover the entire area of possible operating points and therefore does not operate optimally in each operating state.
Furthermore it is known for position controllers for hydraulic cylinder units that a non-linear transformation is undertaken in each case independently for the setpoint position and the actual position and in addition a part linearization of the position controller is undertaken. This method of operation however is very complex.
DE 10 2007 051 857 B3 and US 2010/294 125 A1, which have the same content, disclose a control device for controlling a hydraulic cylinder unit of the type explained above. This control device delivers optimum control results both in position control and also in force control.